Question

D varies directly with t. D is 105 when t is 3.. Find D when t is 8.. A] 35. B] 280. C]841

Answer 1

D = kt

solve for k when D= 105 and t = 3

k = 35

So,

D = 35t

when t is 8

D = (35)(8) = 280

Answer 2

if it varies directly, then u can make a proportion.
105/3 = d/8
cross multiply
(3)(d) = (105)(8)
3d = 840
d = 840/3
d = 280 <===